Presently, there is no known method for the complete interior inspection of the surface of a large diameter bore (greater than one inch in diameter) by optical fiber means. The only method currently available is to use a small diameter optical fiber bore scope and view small discrete areas of the surface of the bore as the field of view permits. This approach is impractical and produces unsatisfactory results since it is restricted by the field of view of the bore scope and there is also an additional problem of holding the focal distance of the scope when inspecting large diameter bores. Using a small diameter bore scope to inspect a large diameter bore has also proven to be very impractical due to the differences in diameters.
To overcome the foregoing problems, some laser scanning systems have become available for inspecting the surface of relatively large diameter bores. These systems can be used to locate reflective spots in the surface of the bore being inspected. Such reflective spots produce electrical impulses, but no permanent image is produced for record and review purposes.
Because of the foregoing limitations with respect to devices available for inspecting the surface of relatively large diameter bores and producing a record of any imperfections and/or discontinuities in same, it has become desirable to develop a fiber optic bore inspection probe that can be used for such inspection and produces a record of any imperfections and/or discontinuities in the bore surface.